The invention relates to a self-supporting composite plate, especially for double floors, with a pan-shaped outside wrapping to hold filler material which is flowable or feedable and hardenable, with high compression resistance when hardened, e.g. anhydrite, concrete or the like.
A self-supporting composite plate of this type is known from German Patent No. 2,004,101. The pan-shaped wrapping of this composite plate has a practically planar bottom and its total unobstructed section is filled with anhydrite or the like, so that the composite plate is correspondingly heavy. In many cases, however, a lightweight plate is preferred, but without loss of the numerous advantages of this composite plate, e.g. the great fire-resistance, carrying capacity, impact sound insulation and so forth.
Double floor plates are also already known from German Patent Nos. 3,103,632 and 2,930,426, which have numerous burl-like projections on their bottoms, which however are totally supported on a foundation, and a plurality of supports are thus formed. These double floor plates may be lighter than the aforementioned composite plates, but they are not self-supporting, i.e. cannot be supported exclusively at their corners on footrests, because the wrapping required for this is not present.
U.S. Pat. No. 4,411,121 discloses a double floor plate of steel, which includes a planar cover plate, welded onto the apexes of a plurality of cupola-shaped projections as well as onto the surrounding, upward-curved edges of a bottom part. This double floor plate is also relatively heavy, but its main drawback is that, if a fire breaks out in the hollow space of the double floor, there is practically unhindered heat transmission in the space found over it with all of the inherent disadvantageous results, because of the metal connection of the bottom with the top of the plate.